According to the United States Census Bureau, the CDP has a total area of 6.6 square miles (17.1 km2), of which 6.2 square miles (16.1 km2) is land and 0.39 square miles (1.0 km2), or 5.93%, is water.[1]

There were 6,212 households in 2010, out of which 34.6% had children under the age of 18 living with them, 60.2% were headed by married couples living together, 9.4% had a female householder with no husband present, and 27.1% were non-families. 23.3% of all households were made up of individuals, and 12.1% were someone living alone who was 65 years of age or older. The average household size was 2.71, and the average family size was 3.24.[3]

In the CDP the population was spread out with 23.3% under the age of 18, 6.6% from 18 to 24, 23.4% from 25 to 44, 29.4% from 45 to 64, and 17.2% who were 65 years of age or older. The median age was 43.3 years. For every 100 females there were 93.7 males. For every 100 females age 18 and over, there were 90.8 males.[3]

Over the period 2007-2011, the median annual income for a household in the CDP was $92,921, and the median income for a family was $106,128. Males had a median income of $78,882 versus $55,872 for females. The per capita income for the CDP was $37,980. About 1.6% of families and 3.3% of the population were below the poverty line, including 2.6% of those under age 18 and 6.3% of those age 65 or over.[4]

The Kings Park Psychiatric Center was built by Kings County (before becoming part of New York City) in 1885 after Dr. Oliver Dewing's successful campaign to develop a hospital for the mentally ill on an 870-acre (3.5 km2) plot of land. The hospital was originally called Kings County Farm, a care center for the poor and mentally ill operated by Brooklyn officials. Kings County Farm is the origin of the name Kings Park.

In 1954 the Center's patient population peaked at 9,303. The Center was a key source of employment for the area during this time period, and was perhaps the most important factor in the hamlet's development.

Increasing costs to run hospital facilities and changing views about integrating the mentally ill into the population at large led to a large-scale movement of patient population back into society. As patient totals declined, so did employment at the center. The decrease in state employment caused a demographic shift, as an increasing percentage of the population became employed in New York City. There are numerous studies tying this deinstitutionalization of mentally ill patients to increased homelessness and crime in New York City in the 1970s.

In 1996, the KPPC property closed. The remaining patients were transferred to Pilgrim Psychiatric Center. The waterfront portion of the former hospital was reopened as Nissequogue River State Park in 2000. Also, the rail spur was converted to a bike path in 2003. The State of New York has abandoned a deal to sell the property to Cherokee Northeast/Arker Companies for remediation and future redevelopment. The plans have been opposed vehemently by many townspeople, most notably the Kings Park Coalition Against High Density Housing, and has become an important political issue in many local political campaigns. Other development options for the property have included a Long Island Rail Road service facility as well as a college campus.

Sunken Meadow State Park borders Long Island Sound and is accessible by the Sunken Meadow State Parkway. It is a part of the New York State Parks system. In addition to the water, the park boasts 6 miles (10 km) of public trails and 27 holes of golf. The park's facilities make it ideally suited for many activities, among them various distance running competitions. The infamous "Cardiac Hill" is well known by local runners.

The Nissequogue River, 6 miles (10 km) in length, empties into Long Island Sound and is readily accessible for all manner of water activities. The scenic river snakes through the recently christened Nissequogue River State Park.

Kings Park is the hometown of Houston Astros catcher/second baseman/outfielder Craig Biggio. Biggio has been named one of the five greatest second basemen of all time by renowned baseball statistician Bill James. He is also the modern-era record-holder for HBPs with 273, and the only player in history to be named an All-Star at both the catcher and second baseman positions.[citation needed]

Kings Park was home to the Long Island Kingsmen Drum and Bugle Corps from 1965 to 1984. The Kingsmen were the American Legion National Champions in 1978 and 1979 and the VFW National Champions in 1979. The corps placed 21st in 1979 and 16th in 1980 at the Drum Corps International (DCI) World Championships.